As the error was finished with the god Indra, he grants Hanuman a desire that his entire body can be as sturdy as Indra's Vajra, and that his Vajra also can not harm him. As well as Indra other gods have also granted him needs: the God Agni granted Hanuman https://travismvkzo.suomiblog.com/little-known-facts-about-hanuman-52602982